[IMP] analytic, *: Json field for analytic distribution

The `analytic_distribution` field is a Json.
It was stored temporarily as a char.

Search is not available yet, so we do queries by hand when we need to search on keys.

Also added a constraint on account_analytic_distribution_model,
so we don't have models with accounts specific to a company when the model has no company or another company.
It would cause an issue when looking at the models from another company.

Part-of: odoo/odoo#101701